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A plant uses energy from the Sun to make food. What kind of energy transformation is this?

Katarina [22]

Light to chemical (C)

4 0

4 years ago

A person standing 1.20 m from a portable speaker hears its sound at an intensity of 5.50 ✕ 10−3 W/m2. HINT (a) Find the correspo

iris [78.8K]

Answer:

PART A)

L = 97.4 dB

PART B)

$I = 6.11 \times 10^{-6} W/m^2$

PART C)

L = 67.9 dB

Explanation:

PART A)

level of sound is given as

$L = 10 Log\frac{I}{I_o}$

now we have

$L = 10 Log\frac{5.50\times 10^{-3}}{10^{-12}}$

$L = 97.4 dB$

PART B)

Since source is a spherical source

so here the intensity of sound is inversely depends on the square of the distance from the source

$\frac{I_2}{I_1} = \frac{r_1^2}{r_2^2}$

$\frac{I_2}{5.50 \times 10^-3} = \frac{1.20^2}{36^2}$

$I_2 = 6.11 \times 10^{-6} W/m^2$

PART C)

level of sound is given as

$L = 10 Log\frac{I}{I_o}$

now we have

$L = 10 Log\frac{6.11\times 10^{-6}}{10^{-12}}$

$L = 67.9 dB$

3 0

3 years ago

A basketball player standing up with the hoop launches the ball straight up with an initial velocity of v_o = 3.75 m/s from 2.5

denis23 [38]

Answer:

a) The maximum height the ball will achieve above the launch point is 0.2 m.

b) The minimum velocity with which the ball must be launched is 4.43 m/s or 0.174 in/ms.

Explanation:

a)

For the height reached, we use 3rd equation of motion:

2gh = Vf² - Vo²

Here,

Vo = 3.75 m/s

Vf = 0m/s, since ball stops at the highest point

g = -9.8 m/s² (negative sign for upward motion)

h = maximum height reached by ball

therefore, eqn becomes:

2(-9.8m/s²)(h) = (0 m/s)² - (3.75 m/s²)²

h = 0.2 m

b)

To find out the initial speed to reach the hoop at height of 3.5 m, we again use 3rd eqn. of motion with h= 3.5 m - 2.5m = 1 m (taking launch point as reference), and Vo as unknown:

2(-9.8m/s²)(1 m) = (0 m/s)² - (Vo)²

(Vo)² = 19.6 m²/s²

Vo = √19.6 m²/s²

Vo = 4.43 m/s

Vo = (4.43 m/s)(1 s/1000 ms)(39.37 in/1 m)

Vo = 0.174 in/ms

6 0

3 years ago

Define thermopile and peltiers??

NikAS [45]

Answer:

Thermopile is an electronic device that converts thermal energy into electrical energy.

A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current.

3 0

3 years ago

A spring hangs from the ceiling with an unstretched length of x 0 = 0.35 m . A m 1 = 6.3 kg block is hung from the spring, causi

Jlenok [28]

Answer:

x₂=0.44m

Explanation:

First, we calculate the length the spring is stretch when the first block is hung from it:

$\Delta x_1=0.50m-0.35m=0.15m$

Now, since the stretched spring is in equilibrium, we have that the spring restoring force must be equal to the weight of the block:

$k\Delta x_1=m_1g$

Solving for the spring constant k, we get:

$k=\frac{m_1g}{\Delta x_1}\\\\k=\frac{(6.3kg)(9.8m/s^{2})}{0.15m}=410\frac{N}{m}$

Next, we use the same relationship, but for the second block, to find the value of the stretched length:

$k\Delta x_2=m_2g\\\\\Delta x_2=\frac{m_2g}{k}\\\\\implies \Delta x_2=\frac{(3.7kg)(9.8m/s^{2})}{410N/m}=0.088m$

Finally, we sum this to the unstretched length to obtain the length of the spring:

$x_2=0.35m+0.088m=0.44m$

In words, the length of the spring when the second block is hung from it, is 0.44m.

3 0

4 years ago